Various types of planar element viewers are known. They may be simple enclosures for use with photographic prints or they may be picture frames used in combination with slide projectors. Various types of slide cassettes allow a stack of pictures to be viewed in succession without having to handle them. The order of the pictures in the cassette having been once arranged can be maintained through various viewings.
Many of the conventional viewers available are expensive and very complicated in their construction because of the many moving parts and the extensive use of various mechanical parts and springs. Many times a negative result occurs through mishandling when planar elements such as photographs and slides are not kept in order or are damaged. It is therefore an object of this invention, among others, to provide a display apparatus which is simple to manufacture, has a high operating reliability and which protects the elements from scratches, abrasions and other damage.
The present invention solves the problem of damage to the face of the planar elements by providing a detaching means at the side of the stack of pictures next to the display window. The detaching means comprises a stop protruding near the open end of the outer box transverse to the direction that the carriage is withdrawn from the outer box and having a thickness not more than the thickness of a planar element. The carriage is provided with a pair of edge walls or guide walls which hold the sides of a stack of elements, and which is further provided with a rigid receiver which carries the bottom of the stack of pictures over a bearing surface located on the bottom of the box opposite the viewing window. When the carriage is pushed into the outer box, the element nearest the window and which has been detached from the stack, is deposited on the bottom element bearing surface and is supported by the bearing surface at its rear transverse edge. The receiver then accepts the detached element and transports it to the bottom of the stack in the carriage.
One object of the invention is to avoid the use of springs to remove the upper most element from the stack. In its normal operational mode, with the display window facing upward and the upper most picture visible, the detached elements will fall to the bottom of the box and thus are in a position to realign themselves to the bottom of the stack. Another consideration of this invention is that if the elements are photographic prints they have a tendency to assume a transverse curature, convex to the side of the picture, and/or can be slightly deformed in the same way by simply squeezing the stack of pictures from the direction of the long individual edges before placing them in the carriage. Due to the existing or imposed transverse curvature, the longitudinal stress of the elements is increased and the longitudinal curvature is eliminated. When the upper most element is detached, there is a natural tendency of the element to return to its natural state of flex which assures that the picture will be released from the carriage. Since the photographs have a tendency to arch, the number of elements in the stack is not critical. In other words, a carriage designed for a predetermined number of elements can accept a few more elements or a few less elements, because the height of the stack adjusts itself automatically to the desired height by causing an increase or decrease in the curvature of the individual elements which insures that the top element will engage the detaching means. If too few pictures are inserted, one can turn the box over so that the window faces downward, and pull the carriage out. With the carriage still withdrawn, turn the box over so that the window is facing upward. This causes the detached element to fall downward and when the carriage is pushed in, the fallen element is restacked on the bottom of the stack. Finally, the tendency of the pictures to assume a slight curvature facilitates the engagement of the pictures with the said receiver. This overall design results in a planar element storage and display apparatus which is easily constructed and has a high reliability during operation, especially in the operation of the detaching means and the restacking means.
In accordance with the preferred embodiment, the detaching means shows a clamping device, which is frame shaped and is located near the display window side of the box. Said clamp is canterlevered at at one end and attached opposite the open end of the box just under the top of the box near the window. The clamping device has a window aperture and/or a transparent window piece.
The clamping device holds the upper most element a distance from the inside top of the box and the box window. The clamping device may be decorated and serve as a decorative frame for the top element. The primary function of the clamping device, however, consists of providing a balance between varying numbers of elements in the stack and/or the different resilient properties of the elements and to ensure that even with minor differences in the height of the stack the top element will be engaged by the detaching means.
In order to stabilize the clamping device when the carriage is pushed in, at the drawing end of the carriage, a handle is provided, which has a recessed slot for receiving and holding the free end of the clamping device when the carriage is totally pushed into the box.
In order for the detached element to engage a receiver at the bottom of the carriage, only the side edges of the element may be supported. To accomplish this while utilizing the transverse curve of the element, the preferred embodiment has a tongue-like projection at the leading edge of the floor of the carriage. Said projection has a wedge-shaped surface that rises toward the bearing surface of the floor of the carriage which carries the stack of elements. Guide pieces, projecting from the side walls of the tray, near the feed end are assigned to said projection, and define the limit of the transverse sides of the stack of elements.
The feed slots for the side edges of the detached elements are left open between the bottom of the element and the floor of either the box or the carriage. The wedge surface extends under the front edge of the bottom of the stack thus facilitating the restacking of the detached element with the stack.
Each individual element in the stack can have a different transverse curvature. It is recommended that each detached element be placed at the bottom of the stack with as little transverse curvature as possible. To align the detached element, the tongue-like projection and the guide piece interact together. To flatten even severely curved elements and restack them with certainty at the bottom of the stack, the bottom side of each guide piece can be slanted perpendicularly to the direction of the wedged surface of the tongue-like projection at the edge of the floor of the carriage, the two of said surfaces forming a funnel-like inlet at each guide piece which inlet has at its narrowest point the approximate thickness of one element.
In order for the element to move freely from its arched condition to a flattened condition, the tongue-like projection can have a wide middle piece and the edge pieces can have slots so that the element is supported by the receiver only in the middle and at its edges. Thus as the element is moved through the inlets, it is flattened by the guide pieces.
The guide pieces can serve a dual function. Each guide piece has an upper guide surface which together with the clamping device form edge guides for the withdrawn element while limiting the downward movement of the clamping device.
Finally, in order to have a smooth operation at the end opposite the open end of the box, a stop for the rear edge of the withdrawn picture is provided with recesses therein to receive the tongue-like projection of the receiver and the guide pieces.
Other objects and many of the attendant advantages of the invention will become readily apparent from the description when taken in conjunction with the accompanying drawings.